The most widely used grade of tolylene diisocyanate (sometimes hereinafter referred to as TDI) for making polyurethanes is a mixture containing about 80 percent 2,4-isomer and 20 percent 2,6-isomer. There is, however, a continuing demand for nearly pure 2,4-tolylene diisocyanate and for an isomer mixture containing about 65 percent 2,4-isomer and 35 percent 2,6-isomer of tolylene diisocyanate. A number of routes are available for the preparation of 2,4-tolylene diisocyanate. These include separation of 2,4-dinitrotoluene from the mixed nitration products of toluene, followed by reduction to the 2,4-diamine and phosgenation. Static crystallization of mixtures of the isomers of tolylene diisocyanate has also been suggested as means of obtaining refined 2,4-tolylene diisocyanate. In particular, U.S. Pat. No. 3,217,024 describes a two-stage static crystallization process which permits the preparation of 2,4-tolylene diisocyanate of acceptable purity. Both of these processes require large expenditures for equipment. The procedure described in U.S. Pat. No. 3,217,024 indicates that partial crystallization of the 2,4-isomer from an agitated mixture of 2,4- and 2,6-tolylene diisocyanate yields a viscous slurry of 2,4-isomer crystals in mother liquor which is difficult to separate by filtration or centrifuging. There is a need in the industry for a relatively inexpensive and simple means for recovering substantially pure 2,4-tolylene diisocyanate from a mixture of its isomers.